1. Field of the Invention
The present invention relates to a rotary connector for electrical connection to be performed by using a flexible cable between a pair of rotatably connected housings and, more particularly, to a locking mechanism for holding the housings in the neutral position of rotation until completion of installation of the rotary connector to a steering system of an automobile.
2. Description of Related Art
The rotary connector is roughly comprised of a pair of housing which are rotatably connected, and a flexible cable wound in an annular housing space defined between the housings; both ends of the flexible cable being fixed to the housing and, in this state, electrically led out. When the movable housing is turned clockwise or counterclockwise in relation to the stationary housing, the flexible cable is wound or unwound in the housing space in accordance with the direction of rotation, thereby, in both states, keeping electrical connection between these housings through the flexible cable.
In the rotary connector, the housing on the stationary side is attached to a combination switch which is a stator member of the steering system, and the housing on the movable side is attached to the steering wheel which is the rotor member of the steering system respectively. The rotary connector thus configured is used as a means of electrical connection for an air bag inflator, a horn switch, etc. In this case, the rotary connector is required to turn by about the same amount in either of the clockwise and counterclockwise directions from the neutral position of rotation of the steering wheel. Therefore, there has been known a locking mechanism so adapted as to hold the housing in the neutral position of rotation until installation of the rotary connector to the steering system is completed.
In a locking mechanism of a heretofore known conventional rotary connector, as disclosed in for example Japanese Utility Model Publication No. Hei 6-47882, the locking member made of a synthetic resin is formed unitarily with a remaining fixed portion, a pull-off portion, and a locking piece. Between the remaining fixed portion and the pull-off portion is formed a thin portion. Using this locking member, the housings are locked from free rotation. That is, at the final stage of the rotary connector assembling procedure, the remaining fixed portion of the lock member is held in an engaging hole of one of the housings which are aligned in the neutral position of rotation, and the locking piece of the locking member is locked to a rotation restricting portion of the other housing. Thus the housings are locked from free rotation by the locking member. This state is kept on until immediately before the installation of the rotary connector to the steering system. When the pull-off portion of the locking member is pulled off from the locking piece at the thin portion after the rotary connector is installed to the steering system, the housings are unlocked and the movable housing now becomes rotatable in synchronization with the turning of the steering wheel.
According to the conventional locking mechanism described above, the angle of rotation of the movable housing set in the neutral position of rotation is restricted to prevent free rotation of the housings, thereby holding the housing in the neutral position of rotation. If the angle of rotation of the movable housing thus restricted in the locked state increases large, the locking mechanism will fail to perform its inherent function. In the locked state, therefore, it is necessary to lock the movable housing from turning, or to restrict the angle of rotation to allow rotation only within a narrow range of play. If, in this case, the rotary connector is left as locked, various tests can not be conducted by turning the movable housing.
For example, there has recently been adopted such an operation procedure that, using the rotary connector and a combination switch which are integrally formed prior to installing these components to the steering system, a canceling mechanism of the combination switch is operated by means of the turning force of the movable housing of the rotary connector. In this case, if both housings of the rotary connector are held in the locked state by using the conventional locking mechanism previously stated, it will become impossible to test whether or not the canceling mechanism normally operates. The canceling mechanism functions to automatically return to the center position the operating lever of a headlamp switch provided in the combination switch. In the case when the canceling lever of the canceling mechanism is projected into the range of canceling turn provided in the movable housing, the canceling lever is driven with the rotation of the movable housing in interlock with the steering wheel, thereby allowing the operating lever to automatically return from the right or left position of operation to the center position when the steering wheel is turned to the neutral position.